This invention relates to moisture separators and moisture separator reheaters and in particular to such devices in which inertial moisture separator elements are employed.
In some electrical power-generating systems, the quality of steam produced to drive a turbine-generator combination is not as high as desired. Following passage of this relatively low quality steam through the high-pressure stage of the turbine, it is often necessary to treat the exiting steam prior to introducing it into the intermediate or low-pressure sections of the turbine. This reconditioning generally involves separating out moisture from the steam and then, if desired, reheating the dried steam to a temperature more nearly approximating the temperature of the steam entering the high-pressure turbine stage. This function is carried out by a moisture separator or a combination of a moisture separator and reheater. U.S. Pat. No. 3,713,278 issued to Edward H. Miller, the inventor herein, and Stephen Chesmejef and assigned to the same assignee as the instant invention, describes a combination of a moisture separator and a reheater contained within the same unit. The contents of this patent are hereby incorporated herein by reference as background material for the present invention.
The function of moisture separation is generally carried out through a sequence of zig-zag shaped chevron plates, or "wiggle plates" as described in FIG. 5 of the aforementioned Miller patent. Such a configuration of wiggle plates is generally described as an inertial moisture separator since it is the inertia of the moisture within the steam that causes it to collect in the cul de sacs as shown. The moisture in these vertical cul de sacs then drains into a common trough from which the water is collected and cycled to other parts of the steam generation system. For more efficient operation of the inertial moisture separators, it is desirable that there be a relatively uniform pressure distribution between the various channels formed by the wiggle plates.
The importance of uniformity of flow into and through the moisture separator elements is recognized in U.S. Pat. No. 4,016,835, issued Apr. 12, 1979, to Abraham L. Yarden and Robert A. Weisberg. To provide the desired uniformity of flow, they appear to employ a perforated metal plate lying substantially parallel to the moisture separator banks. Fixed to this metal plate are solid baffles arranged in a staggered fashion acting to produce variable pressure drops to effect the desired uniformity. However, the presence of pressure drops generally acts to reduce the useful energy content of the steam. It is to be particularly noted in the patent to Yarden et al that the perforated plate lies in a direction parallel to the longitudinal or cylindrical axis of the cylindrical pressure vessel and that the variously shaped and staggered unperforated plates lie in a direction perpendicular to the perforated plate and parallel to the cylindrical axis of the pressure vessel.